Patients who are forced to sit for prolonged periods of time often experience decubitis ulcer (pressure or bed sore) problems due to the length of time they are forced to sit. The concentrated pressure upon the patients' Ischia (bony, downward projections from the pelvic girdle) caused by prolonged sitting often leads to ulceration of the tissue between the seating surface and the bony, Ischial protrusions.
U.S. Pat. No. 4,688,285 of Robert discloses a medical cushion for minimizing pressure areas on portions of the human anatomy. This cushion contains an aperture extending completely through the cushion from its top to its bottom. However, the cushion of this patent does not substantially eliminate pressure upon the Ischia of a patient; and, because of the location of its aperture, it is relatively difficult to use. Furthermore, because the cushion consists essentially of only one foam material, it does not provide the proper blend of resilience and support required for long term use by patients.
U.S. Pat. No. 2,257,848 of Larkin discloses a hip rest for patients comprised of a rigid material, such as wood. Although the hip rest of Larkin provides sufficient support, it is too rigid and uncomfortable to use, especially for relatively active patients who are subjected to jarring loads.
U.S. Pat. No. 4,122,567 of Hanson discloses an articulated bed having a U-shaped cavity along one of its ends. The function of the Hanson device is to facilitate sexual intercourse between two people supported upon the bed. There is no disclosure in Hanson of means for minimizing pressure upon the Ischials of a person sitting on the mattress, and the mattress of Hanson does not appear to have the combination of resilience and support required for a pressure relief cushion.
U.S. Pat. No. 2,085,296 of Carey describes an invalid cushion with two cloth sheets that are stitched together to provide a pocket for padding. The cushion of this patent does not appear to provide the proper blend of resiliency and support; furthermore, the aperture in this patent is located such that it is relatively inconvenient for a patient to use.
U.S. Pat. No. 3,833,259 describes a vehicle seat containing three layers of polymer foams. However, the cushion of this patent does not provide any means for eliminating pressure upon the Ischial area.
It is an object of this invention to provide a cushion which will tend to substantially eliminate pressure upon a patient's Ischial area when he sits upon it.
It is another object of this invention to provide a cushion which will provide a unique combination of resiliency and support.
It is another object of this invention to provide a lightweight cushion which can be readily handled by invalids.